The function "getRobotModel()" is a member of PlanningScene and not a member of this class. However because of the "operator->" here which returns a PlanningScenePtr, this works.

Only one of these "ReadWrite" locks can exist at a given time. The intention is that users which need to write to the PlanningScene will use these, preventing other writers and readers from locking the same PlanningScene at the same time.